Open QuickTime Player
Click File
Click New Screen Recording
Click the arrow next to the Record button
Select your microphone
Click Record
Choose Full Screen or drag to select an area
Click Stop in the menu bar when finished
To record system audio, install a virtual audio driver such as BlackHole or Loopback
Set the virtual audio driver as the Mac’s audio output
Set the same virtual audio driver as the input in QuickTime or your recording app
Use a screen recording app like OBS Studio if you want easier audio capture
In OBS Studio, add Display Capture
Add Audio Input Capture for your microphone
Add Audio Output Capture or the virtual audio device for system audio
Click Start Recording
Click Stop Recording when finished