How will Zoom track if I have my camera on but I am not actually there

[6legstiger]

We have this class that requires the camera to be on. The host said that Zoom can track how long your camera is on. If I upload a short video of myself and use it as a background while pointing my camera at a white wall, so in this case other people will see my pre-recorded background with me in it. Will Zoom be able to track if my face is not actually showing in my camera, even though nobody is there and only my background is visible? Will the host have access to this info?