I can...

If you have already added the hair, use the Snapping tool (keyboard [S] or the magnet on the left toolbar. Then choose the snapping point on the top of the head.

If you haven't added it yet, click on the snap point on the top of the head. Then add your hair and it will snap to the top.

These techniques work for any part... although the snap points aren't always in the exact spot you need or in the orientation, but they usually get you close enough that the medium grid spacing will allow you to place the part exactly where it needs to go.