How to use a bug finder
Updated: 22 October 2026
You already have a handheld detector, it is beeping in the hallway, and you need the order of a room check rather than another ranking. How to use a bug finder means switching off radios you already know about, walking slowly, then reading the alert as energy. A beep means radio energy nearby. Silence means this pass heard nothing. The [bug finder comparison](/hub/electronic-surveillance/bug-finder) is where the twelve models sit. This page does not pick a winner. This page is from Peter F., editor for DIY & tools. The steps come from amazon.co.uk review notes and public UK sources, not a lab sweep.
You already have a handheld detector, it is beeping in the hallway, and you need the order of a room check rather than another ranking.
You already have a handheld detector, it is beeping in the hallway, and you need the order of a room check rather than another ranking. How to use a bug finder means switching off radios you already know about, walking slowly, then reading the alert as energy. A beep means radio energy nearby. Silence means this pass heard nothing. The bug finder comparison is where the twelve models sit. This page does not pick a winner. This page is from Peter F., editor for DIY & tools. The steps come from amazon.co.uk review notes and public UK sources, not a lab sweep.
Our top picks
| Badge | Product | Control | Quiet alert | False alarm | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  SFILOFEREE SFILOFEREE T19 | Six levels | Not stated | Phone, and LEDs | 7.8 | about £29.99 | View offer |
 SIKVIO SIKVIO K18 | Potentiometer | Not stated | Wi-Fi, loud beep | 8.6 | about £44.99 | View offer | |
| Best value |  HawkSpy HawkSpy K18 | Knob | Vibration listed | Antenna if touched | 8.3 | about £40.92 | View offer |
Before you switch it on
Start with the transmitters you brought in. A Mystery Code bullet says to turn off your phone, router, and other wireless devices. A SIKVIO review describes a useful pass only after Wi-Fi was off and the phone was in flight mode. AOBOCAM reviews name Wi-Fi, Bluetooth, routers, and smart TVs as the things that trip the alert. If the router stays on, the first beep is the building. Charge the stick first. Most boxes list a USB cable rather than a BS 1363 charger, and a FOWARD GAUSS review says a unit would not hold a charge. A dead cell is a failed check. Ofcom’s receive-only exemption is not permission to listen to a call or a feed.
The pass itself
Walk slowly, close to surfaces you can lawfully inspect: skirting, sockets, clocks, smoke-alarm housings you can see without dismantling them, and the edges of furniture. Confirm the stick is awake on a phone you switch on for a second, then off again. Lower the control as you close in on a beep. The SIKVIO lists a potentiometer, the HawkSpy a knob, and the T19 six levels. The XiflLife bullets claim five levels and the FOWARD GAUSS bullets claim ten. K-68 reviewers could not set a middle between nothing and everything, so do not invent one. Do a second pass after a few minutes, because trackers often transmit in bursts. A magnetic probe has to be against the surface. K20 and K-68 reviews put that range at a few centimetres, not from the driver’s seat. When the camera may be silent, use the RF detector or lens finder page.
What the alert is saying
A beep next to a powered router is the router. A false positive can be a working detector on real Wi-Fi. A false negative is the more serious error. The HawkSpy also alarms when you touch the antenna, so that beep is the aerial. The T19 false-beeps beside a phone unless you lower the sensitivity, and one unit alarmed around LEDs while detecting nothing else. If the stick sings at every lamp and will not silence, treat it as faulty. Vibration is stated for the HawkSpy, the AOBOCAM, the XiflLife, and the Souhpyh, and not for the SIKVIO. Silence means this walk heard nothing. A card camera, a wired camera, and a tracker between bursts can sit inside that silence. Hotel reporting is on the hidden camera detector hotel room page.
When you stop
Stop when you suspect a skilled installation, when you need evidence, or when you cannot separate the alarm from the building’s radios and the stakes are high. FCDO Services treats a professionally installed device as work for a technical-surveillance team. In a private setting, tell the police on 101. Do not search someone else’s vehicle or property. Do not decode or record the content of a signal. A strength beep is as far as these detectors go. The Wireless Telegraphy Act 2006, section 48, and the Investigatory Powers Act 2016, sections 3 and 4, deal with message content you are not meant to receive.
Common questions
What does a beep next to the router mean?
It means radio energy at the router, which is what a working detector does. It does not identify a bug. Turn the sensitivity down, or switch the router off if it is yours, and see whether a nearer beep remains. If the only beep was the router, you have checked a known source, not cleared the room.
What does silence mean?
Silence means this pass, at this sensitivity, did not hear a transmission and did not see a magnet within the short range of the probe. It does not mean the room is safe. A camera that is off, wired, or recording to a card can be silent on radio, and a tracker can transmit in a burst you missed. A second pass, and a lens check if your unit has a window, are the limits of the stick.
When do you use vibration instead of sound?
Use vibration when the room has to stay quiet, such as a night check in a hotel, and only on a unit whose listing or reviews state it. That is the HawkSpy, the AOBOCAM, the XiflLife, and the Souhpyh in this set. The SIKVIO file does not state vibration, and a review already calls its beep loud. Vibration does not change what the alert means. It only changes who else hears it.
At what point do you stop and call a professional?
Stop when you suspect a skilled installation, when you need evidence for the police, or when you cannot tell the stick’s alarm from the building’s radios and the consequences are serious. FCDO Services treats that as specialist work. In a private setting, contact the police on 101. Do not keep buying passes with a consumer detector and call the result a clearance.
Are you allowed to listen to the content of a signal you find?
No. These steps use signal strength only. Obtaining or disclosing the content of a message you are not meant to receive is covered by the Wireless Telegraphy Act 2006, section 48, and the Investigatory Powers Act 2016, sections 3 and 4. Ofcom will not give you case-by-case legal advice on a particular recording. Leave the audio and the picture alone.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 20 October 2026.
- Investigatory Powers Act 2016, sections 3 and 4 (retrieved 20 October 2026)
- Wireless Telegraphy Act 2006, section 48 (retrieved 20 October 2026)
- Ofcom, Radio spectrum and the law (retrieved 20 October 2026)
- Sexual Offences Act 2003, section 67 (retrieved 20 October 2026)
- GOV.UK, Covert surveillance and property interference code of practice (retrieved 20 October 2026)
- FCDO Services, Detecting hidden cameras at work (retrieved 20 October 2026)
- Consumer Rights Act 2015, section 9 (retrieved 20 October 2026)
- amazon.co.uk, SIKVIO K18 listing (retrieved 20 October 2026)