Hux has been hiding his Force powers his whole life after seeing how fucked up Kylo Ren got under Snoke's tutelage. He also uses them to hide, literally making himself invisible to others, blending into shadows, not being heard by people he doesn't want to be heard by, and of course the mind trick. Hux assumes this means he's on the Dark Side of the Force because those just sound like Dark Side powers to him.

But he has a conscience and he can only drink away so much of his guilt after hours, so he makes a break for it to go find the Resistance. How? With the Force Ghost of his grandfather/great uncle Obi-Wan's guidance and a lot of blatant abuse of power, that's how!