Rotate around a point with a specific angle

I would like to rotate/position a gameobject around a point with a specific angle selected with a slider.

I have a start point, were the rotation angle equals 0. Depending on the value of the slider, i would like to rotate the gameobject around the point. The slider value goes from 0 degree to 360 degree.

I am not very familiar with Quaternions and very new with Unity, too. Is there any easy way to fix this problem?! I checked transform.RotateAround(). But it adds every frame the selected angle over the slider to the existing angle.

thank you very much for your help :)