HTC Vive Instantiate Object Directly Into Hand

Hi Guys,

I'm working on a VR project with a simple idea, similar to a dart game: when the player presses the back button on the controller, a sphere is spawned in the exact position of the hand, when the button is released the sphere either falls down or gets thrown away.

This video shows exactly that, I just can't find any way to get there:

So far I can interact with objects through steamVR scripts, and I'm able to spawn them in the center through KeyDown.space. But I have no idea how to 1.trigger the spawn through the controller keys and 2.put the position of the spawned object right into the virtual hand (and holding on to it.)

Super grateful for any help,
it's my bachelors project and there's not much time left!
Merci <3