Bug detectors, though slightly more complex than camera detectors are fairly simple to use. Since bugs transmit RF (radio frequency) signals, bug detectors hone in on those signals and indicate that there is a bug present, by lighting up, making a sound, or both. Please keep in mind that since bug detectors are designed specifically to pick up any RF signal in a given area, you may receive "false" positives if another RF-transmitting device (cell phone, radio, microwave, etc.) is nearby and active while you're doing a bug sweep.
What to do before you start using your device.
Before you begin, you should turn off, unplug, and/or disconnect any communication devices that you are already aware of in the space you’re scanning. Once this is done, turn on your RF detecting device.
Things to keep in mind while scanning.
No matter which type of RF detector you're using, it’s important to take your time with the scanning process and be patient. Some bugging devices may not register a signal immediately, so you may need to continue the scan while waiting for a transmission.
For example, a GPS tracker placed in a vehicle could be programmed to transmit data back to the user who placed it every 10 seconds, or it could be programmed to only transmit every 10 minutes. It depends on how the user programmed the device. Because of this, it may be necessary to turn on the detector and wait until the bugging device you’re looking for makes a transmission. Until that time, a signal will be undetectable.