Hello all!

I'm  working on a theme and I had the idea of making this:

On the pic is the object I want to code - a stick-like object to follow the cursor and always rotate so that it points towards the center of the circle. The only thing I simply can't do is to get the rotation just right. I tried a lot of things but my neglection of trigonometry and math as a whole for the past year has unfortunately left severe consequences

Long story short - I need to calculate the angle of the stick object while knowing only cursor and orb's positions.