Surveillance technology has come a long way since the 1950s when an audio bug approximated the size of a pineapple and you could hear the audible click of a phone tap on your receiver. Today's surveillance equipment is smaller, better, cheaper, and often nearly impossible to detect. Further, in the digital age, your computer has become an easy target for remotely accessing all kinds of personal and financial information. Luckily, counter-surveillance technology has evolved almost as quickly and a little time and vigilance can prevent an estranged spouse or business partner from spying on you.
Perform a "sweep" of your home and office with a standard bug detector. Most surveillance cameras and audio bugs emit radio waves that can be detected with inexpensive devices sold by security equipment vendors. Scrutinize any places in the walls or ceiling that appear spackled or freshly painted. Surveillance equipment can be very small so also examine objects such as pens, clock radios, picture frames and even lamps. Window exteriors are also easy targets because they do not require an actual break-in.
Search your car for bugs as well as GPS devices that track your movements. Common locations include the rear bumper, heater vents and your CD player/radio.
Look for more sophisticated bugs. Many surveillance devices switch radio frequencies or switch on and off to elude detection. Further, the battery of a bug may simply have died (until it gets replaced, of course). However, there are devices that can detect magnetic fields or even the electrical static produced by computer circuitry. Be prepared to find many false positives since non-surveillance devices such as home computers may also possess these qualities.
Secure your home and work computers. At minimum, make sure that you have a solid firewall. Also run counter-surveillance applications such as SpyCop to identify and block trojans and keyloggers (a spyware program that records every keystroke on your computer).
Stay vigilant. Conduct regular "sweeps" of your work and living quarters. Also, the best form of counter-surveillance is preventative. If no one can breach the perimeter of your home, no bugs can be placed in the first place. Consider installing a home security system.