Lens Finder Bug Detector
If you want to know for absolutely sure that nobody is spying on you, you need a bug detector. It can spot hidden cameras or microphones, and find out if there are audio/video transmitters nearby.
One of the most versatile counterspy gadgets around is a Lens Finder Bug Detector. It is easy to use. To find a spy camera, all you have to do is look through the viewfinder. Any camera lens will start flashing red.
To find wireless transmitters, turn this Lens Finder Bug Detector on to RF mode, and slowly go through the room, going over objects that could possibly hide some kind of transmitting device. Signal strength indicator lights will turn on and off so you can actually gauge how close you are to a transmitter.
If you want to conduct your monitoring discreetly, you can switch the Lens Finder Bug Detector to silent mode. It will vibrate quietly when it detects something.