Please find more information here.
Does Blizz support the use of virtual cameras (i.e, iPhone, iPad, USB external, etc) on the Mac OS desktop client?
I am able to use my iOS device on another popular conferencing app, but would prefer to use Blizz.
I am using ManyCam with Blizz.
You can select ManyCam as your preferred camera in Blizz and with ManyCam you can switch between different cameras plugged into your computer.
there is another thread, where you can vote for, so you can run a virtual webcam in the future.