My computer (Librem13v2) does the same (only static from the microphone).
I’ve contacted customer support on this.
On my computer, the camera works, but the microphone does not.
There has been a previous thread on a similar-sounding failure:
In that person’s case, it may have been a loose or broken wire. The microphone is behind a tiny pinhole to the left of the camera, so the microphone wires have to go through the laptop’s hinge.