Hi,
You can add your Mac system as a Jenkins Slave. For that, you can find lots of documents. You can follow the below document to do that same.
https://parsed.io/setup-a-mac-slave-for-jenkins
Now it is very obvious that your machine should always be ON. Otherwise, you can't use that system. For making a slave you don't require any new user. Just set up your Jenkins slave and it will work.