When a player is looking or clicking at something, they fire a ray that goes until it hits what it needs to hit, or misses.
The result of such a hit is an IRayTraceResult object.

It might be required to import the class to avoid errors.
import crafttweaker.world.IRayTraceResult

All you can do is retrieve information from these objects, here's which:
Be careful though, since all getters that do not return a bool can return null!

name	type
name isMiss	type bool
name isBlock	type bool
name blockPos	type IBlockPos
name sideHit	type IFacing

These getters won't actually return anything useful because there isn't a reliable way to raytrace blocks and entities.

name	type	return value
name isEntity	type bool	return value always false
name entity	type IEntity	return value always null