Miracast - use of built in speaker and microphone

Hello ueberhard ,

Miracast works one way, you project from your computer to the Surface Hub.

If you are on a Teams call on the Surface Hub, you can project through Miracast on the Surface Hub and share your Surface Hub screen. 

However, it would be a better experience if you join on the Surface Hub with Audio/Video and share your screen using Teams from your computer (no audio/video). In this way you can take advantage of Surface Hub's camera, microphone and speakers and project your computer's screen through Teams (which will also be visible on the Surface Hub)

Hope this helps,

Cezar