Want to play as a ghoul in Fallout 4? There's a Fallout 4 mod for that.
Playable Ghouls is a very basic mod that allows you to transform your character into a human that's been irradiated by radioactive fallout.
If you start from scratch, your ghoulish customization options are limited to hair. If you transform a character that's already in the Fallout universe, they'll keep everything.
You can get a feel for the mod in the video below.