Can’t you just parent the spot (I assume you mean spotlight?) to the sphere? That would have the same effect with no scripting required. To parent, select the spotlight, select the sphere, and hit ctrl-p. Now when the parent moves, the child (The spotlight) does as well.
Select the light, select the sphere, hit Tab to go into editmode, then select a vertice and hit ctrl-p. Vertices don’t have any orientation, just a position, so your light will simply move with the object and won’t rotate.
For best results, create a vertice at the very center of the object and parent the light to that.