Try starting the ball at the default (starting) position. This goes through the opening and sometimes the ball stays up top — but not always. You may need to maneuver the ball around the bottom of the board and look for an opening to send an angled shot through the gap.
If you get the Gun, destroy the three unbreakable bricks on the bottom right, which will expose the other capsule. Alternatively, destroy the three unbreakable bricks on the bottom left.