If you mean the GPIO ports, then you just need to use the built in components. The homeassistant user already has the correct permissions. If you don’t mean the gpio ports, you might have to explain DIO.
I think you need to explain a little more exactly what you want to do.
Hassbian is just rasbpian with a few extra scripts installed, so whatever you did with Domoticz should be available, but before anyone can explain how to integrate it with HA, they need to know more.