Move a game object between two positions in a sin wave

I have two positions in my scene and I want a sphere game object to move between them. But This is easy enough to do with the move towards command, but what I want to happen is the ball to accelerate when leaving one, then decelerate when approaching the next in a controlled curve.

I was told that I could do this with a sin wave, however I'm unsure how. Is there a simple way to do this ?