Diagonal aiming

So im working on a bowling game, and the way the aiming in the game works is almost entirely based on space bar. When you hold down spacebar, the ball will move laterally across the lane back and forth, and on release will stop moving. Then, an arrow pointing down the lane would begin swing along an arc to aim diagonally. When you press spacebar, wherever the ball will be propelled where your aim is pointing. I know this is basic but I am a comple beginner. So relize that to move the ball diagonally I will need to use AddForce and push along 2 axis, but how would I generate the aiming arrow and animate it to move? Sorry if this question is not very clear, if you need more information I will be happy to provide it. Any help is appreciated, thanks!