Make sure the headphone jack is firmly plugged into the correct audio jack. Make sure your audio source is on and the volume is up. Why can’t I hear the game through my headphones? How do I listen to Audacity while recording?

Microphone: Connect the microphone to the dedicated Microphone port. Audacity does not always immediately recognize the microphone. If Audacity is already open, save your project, quit Audacity, turn on the microphone, and then re-open your project. Not an expert on macOS here – just something to try Try “Transport > Rescan Audio Devices”, then select your speakers. Re: No sound through headphones the output of Audacity goes to the built-in loudspeakers regardless of headphones being plugged in or not. Why is my Audacity not playing through headphones? 9 How do I monitor my voice on Audacity?.