You can't fault them for trying: Operation Acoustic Kitty

In 2001, the CIA disclosed Operation Acoustic Kitty launched by the Central Intelligence Agency Directorate of Science & Technology during the height of the Cold War. It started when the CIA noticed that Russians assigned to almost every Soviet Embassy in the world, would often gather in small circles outside the embassy build and hold hushed conversations. Whatever they were discussing, it was more than probably some sort of dissent, could be valuable information. The problem was, for the US, getting an earful of the discussion.  
At the time, the CIA was testing methods of audio surveillance by inserting miniature microphones (developed by hearing aid manufacturers) into bullets strong enough to withstand the force of a gunshot and still keep recording. These tests yielded smaller, rugged microphones, but no “spy-bullet,” since microphones would pick up all sounds, relevant or not, making most recordings largely useless. So in 1961, the CIA had been conducting successful research in radio equipment and animal training and had worked on creating surgically altered cats (Cats were selected because, like humans, their cochlear anatomy allows them to filter and focus sound.) who were implanted with state of the art acoustic and radio transmission technology. 
The concept was that the cats would be free to wander the ground of the Soviet properties around DC, recording conversions.  At a cost of a remarkable $100 million, a prototype cat had been trained to wander around building and people. In an hour-long procedure a veterinary surgeon implanted a microphone in the cat's ear canal, a small radio transmitter at the base of its skull and a thin wire into its fur, allowing the cat to innocuously record and transmit sound from its surroundings.

CIA officer Victor Marchetti wrote; “They slit the cat open, put batteries in him, wired him up. The tail was used as an antenna. They made a monstrosity. They tested him and tested him. They found he would walk off the job when he got hungry, so they put another wire in to override that. Finally, they’re ready. They took it out to a park bench and said, “Listen to those two guys. Don’t listen to anything else – not the birds, no cat or dog – just those two guys” (It should be noted that Marchetti was a prominent critic of the CIA)
A heavily redacted memo on the project was declassified in 2001, implying the CIA was too embarrassed disclose all the details of the project so there are two version of what happened next. Robert Wallace, a former Director of the CIA's Office of Technical Service, said that the project was abandoned due to the difficulty of training the cat to behave as required,  “The cat” he said “wanted to do what the cat wanted to do, and not what we wanted it to do”  and that “the implant could not affect any of the natural movements of the cat, nor could the cat experience any sense of irritation or the presence of the device, lest it induce rubbing or clawing to dislodge components or disturb performance……. the equipment was taken out of the cat; the cat was re-sewn for a second time and lived a long and happy life afterwards".
The second version is that the cat was driven in a van loaded with equipment to the Soviet Embassy’s communal residence building on upper Wisconsin Avenue in D.C. (The Soviets somehow managed to get a property located at the highest point in the city)  The cat was let out of the van and when it walked across the street was run over and killed by a taxi. The project was cancelled in 1967.