Streaming Tablet as seperate Video input

It would be cool if you could be in a call via PC (i.e. use the desktops mic/camera and show the call on PC) while using your tablet to write down stuff with an E-Pen. Especially for classes during corona this would be really useful, since as a physicist i often discuss handwritten content, which can the only be shared in discord if i am in the call solely via ipad, which gives me worse mic and camera, as well as making it impossible for me to monitor the other participants in a call.