Control the PoE hat fan?

I just got my rockpi, a poe hat and the heat sink. It has been working wonders. When compiling code for a long time I’d like to use the fan to keep temperatures down (even though the heat sink does work wonders).

How do I do it? Is there any simple “just set heat limits and be done with” or do I write my own script to do it?

Best regards
Linus