I'm going to assume by 'object' you mean 'non-actor' (otherwise you'd just use OnHit, right?)
I'm not sure there's a foolproof way to do it at present, though I haven't kept up with developments among the talented pool of scripters here. There are some rough ways to do it if you want to know when the player hits an object, but they don't apply more generally.
Might be best to make a thread over in the CS forum about it.
No, not really. OnHit runs when the target actor is hit by something, what I was asking for is a way to get that "something"'s reference. Kind of like how you can get ProjectileSource
Truth is, I didn't know OnHit can work without ActorID parameter until you said that (I guess I didn't read everything clearly). Maybe what I want can be done with OnHit and doesn't require any dedicated functions, I'll make a thread in CS forum about it. Thanks