Hi WasPedro,
You’ll first need to have an integration of Nvidia’s Hairworks in Unreal Engine 4 since it’s not integrated with the out of the box version.
If you’re wanting to use Hairworks you can follow this thread for information about Nvidia’s separate branch with this integrated that you can get off of GitHub and build the source code.
This forum thread should help get you started: NVIDIA GameWorks Integration - Asset Creation - Epic Developer Community Forums
I hope this helps.
Tim