If you have headphones, speakers and internal speakers set up on a Mac and also a headset, microphone, and internal microphone, you’ll want to easily switch between different inputs or outputs. There is a quick way without going to the System Preferences each time.
Hold the Option key and click the volume icon in the menu bar this will show a list of audio inputs and outputs. You can now select what you want.
This enables you to quickly switch between audio inputs and outputs.