iPad Best app to record whiteboard drawing on new iPad Pro with external USB mic and post to YouTube?

[amin]

I want to make YouTube videos of whiteboard presentations using my new iPad Pro and Apple Pencil 2 along with an external USB microphone.

Is there a recommended app to use for my whiteboard drawings and handwritten text?

I will be recording brief presentations about medical topics in a style similar to Khan Academy.

I don't know if the built in screen recording app will let me use an external mic or whether I need to look for a whiteboard app that comes with its own screen recording.

I need to be able to upload the videos to YouTube.

Thanks for any suggestions!