There is an implant in me, is there a way to identify the frequency it is receiving signals on?
It is very hard to detect a device that is passively receiving a signal, and even more so when it is designed to operate undetected. Some random comments and ideas:

In the UK one has to pay taxes on TV ownership. I read somewhere that they employed a technique to detect unlicensed TVs, which are otherwise passive receivers. I don't know how the technique works, but you may want to research it.

Scanning the spectrum around you is useless. There are hundreds of different signals around us all the time; it will be impossible to detect if any one of them is intended for your implant.

Any receiver must use metal components, so you could use a metal detector on yourself. Get a very small receiver (such as one of the tiny WiFi dongles) and verify that your metal detector can detect it on the other side of your head; it should then be able to detect any device inside your body.