I was working on my night shift as a technician. Everything was normal and I had received another aircraft from their flight. After engines shut down and chocks in place, I connected my headset and welcomed the crew. They confirmed that aircraft was on brakes and everything was OK. I removed my headset and hanged them on the oleo of the nose gear (a standard practice by the ramp personnel). Ramp workers started their duties whilst my duty partner went up to the flight deck for the checks. I started doing the walk-around. At some point I realized that my partner was flashing the nose wheel lights. I went to the front to check what is going on, only to find that my headset was torn in half! Somehow someone managed to completely cut the wire from the plug to the headset. I tried asking the people around, in a very kind manner, but everyone said that they saw nothing. I informed my colleague about the event and again asked him if he saw anyone around the nose-wheel section but he said he saw nothing. I tried to contact the airport operation to check the cameras, but they needed a complicated procedure and an official report in order to go back on the videos. It was not so much about the headset as to the fact that someone damage a piece of equipment and totally avoided any report. It could be something much more serious than this. I filed a safety report to the company and to the airport but nothing came out of the investigation. Too bad some people are afraid so much to take responsibility of their actions.