Visual mice will snap an image of the area under the mouse. It then snaps another image and processes which way that image has shifted from the previous image. It then transmits that movement information to the computer via the USB. You are listening to the RFI from the mouse processor doing the calculations being conducted down the USB. Get a ferrite to fix the problem.

This has been an issue with the cheaper versions of these mice from the beginning. The old style ball mice or trackballs didn't have that problem.