high pitch noise - goes away when brake is applied

I have a 325ci 2003 2.5L while driving there is a high pitch noise that seems to come from under the dash - sounds like it could be from the door chime or any other buzzer alarm - very low volume but high pitch - when the brakes are applied lightly it goes away. Does anyone have a clue what this might be??

Thanks in advance

Just get a normal servicing and the sound will be disappear.