How would I get the mouse position?

(I already tried get_global_mouse_position() but I think that's for 2D)

How would I get this script to get the mouse position and then get the x and y positions of that into variables so that I can put them into the vector and have it launch forward a certain amount in the direction the screen was clicked basically...

extends RigidBody


func _physics_process(delta):
	if (Input.is_action_just_pressed("Space")):
		add_central_force(Vector3(0, 500, 0))
		print("yes")

*I am doing 3D