@Anathematika
Hey welcome to hyperPad! This is possible in quite a few ways. It really depends on your game, and how in depth you want to get.
Lets say it's a gun you want to pick up. You could place a gun in your scene, then use the "Collision Event" behaviour to check your character touches the gun.
From there you could do things like "destroy object" to destroy the gun object from the scene.
Now how would you make your character have a gun?
Well you can add the "shoot with button" behaviour on the object, but have it disabled. And once you collide with the gun, enable this behaviour so it starts working.
Then if you want to do things like make your character look like hes holding a gun, you could do this various ways. Easiest way is to just change the player graphic to one thats holding a gun.
@robinsonx has made a few games like this in the past, so I'm sure he has some ideas as well.