Using Unreal components from outside program / dll

Hello -

Starting some investigation of Unreal architecture / software components / API. New to Unreal. I have developed an application that creates/manipulates meshes (with output to VR): windows / C++ visual studio / opengl / openvr. There are some Unreal’s functionalities that I’m interested in (for instance: collision detection) and I am wondering how to direct my investigation … Any way to “call” some Unreal components from my program? Via an API? What part of the dev forum should I be looking at first? Thx in advance for any help / suggestion !