How to Build a Spy Bug

Updated March 23, 2017

Before building your spy bug, it is important to know that purchasing certain equipment to build spy bugs and tape phone calls can be illegal in different parts of the country. Become familiar with the laws. There are many types of kits available for surveillance, including sound and motion detector items. The most popular spy bugs are microphone devices. There are many ways electronic devices now can connect to one another via mechanisms such as component cables, Ethernet cables, electrical wires and Wi-Fi. Bluetooth is a method of connecting devices that is wireless, automatic and lets you build an effective sound surveillance tool.

Take a moment to consider whether or not you truly want to listen in on someone else's conversation. This is an invasion of privacy that should not be taken lightly. If you decide to move forward with this activity, the following steps will accomplish your goal.

Turn the Bluetooth headset on. The headset must be paired with your cell phone. Instructions that come with your Bluetooth headset will explain how to accomplish this task. Make sure your cell phone is compatible with the Bluetooth. Verify that all batteries are relatively new. Walls of a house won't stop a Bluetooth signal, making it useful for controlling several devices in different rooms.

Conceal the Bluetooth headset in the room where the conversation is intended to take place. Position it in a location that picks up sound clearly. Consider what devices may be in the vicinity of where the Bluetooth will be concealed. For example, if there is a television next to where the Bluetooth will be located, the output from the TV may interfere with the clarity of the Bluetooth recording.

Move into another room and wait for the conversation to begin. Ideally this will be the next room. The Bluetooth connection works through walls but can lose its effectiveness if too far away. A rule of thumb would be a maximum of about a 35-foot distance.

Listen for the beginning of the conversation. Turn on your phone's voice recorder. It will record through the microphone of the Bluetooth headset. Turn off the recorder at the end of the conversation. Recover the headset from the place of concealment.

Play back the recorded conversation.


Perform a test using your Bluetooth and various distances to confirm that it will work satisfactorily. Ideally, test the Bluetooth in the actual location of the intended conversation. Check to see that the voices will record clearly.


Disclaimer -- make sure you are in accordance with the law in regard to the use of these spy bugs.

Things You'll Need

  • Bluetooth headset
  • Cell phone
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