If you’re interested in some of the earliest and most technologically fascinating covert listening devices, there is no better example than Theremin’s bug.

A "bug" was found today in the office of the Commander ... According to him, the discovered information reading devices are made from components of an unidentified model, making it impossible ...

Ukraine’s military chief said that a covert listening device was found in one of the offices where he works. Bugs were also detected in other locations, Ukrainian army Cmdr. Valeriy Zaluzhnyi said.