Is there a way to find is the user has clicked the 3D model or the space around it?
Sure!
(And this would be a complete answer to your question, because you have asked “is there”. 
)
But if you are interesting how to implement selection/picking, then it’s a different story, and depends on many things.
If you are using fixed functionality (without shaders), then standard OpenGL picking would serve the purpose. The whole chapter in the Red book is devoted to this topic (OpenGL Programming Guide 7th Ed. Ch 13 pg.605-627).
Everything explained in 13th chapter of Red book is deprecated since GL 3.1. So, if you want to use core profile and GL 3.1+, then color picking or custom ray caster is the solution.