When they drop the ball in the wheel, there's forces acting on the ball that cause it to end up on one of the numbers. There are a series of events, that are not based on chance, that govern where the ball is going to end up landing. It is an incredibly complicated list that is practically impossible to measure/calculate. So, from your point of view, it looks like the ball is just landing on a random number and that it gets there by chance.
From the point of view of the ball and all the forces acting on it, there isn't actually any chance involved - all the numbers that come up are just a result of the processes that the ball goes through.
But from your point of view all those process are invisible so as far as you can tell it is all just a result of chance.
We know that it's the occurrence of a mutation (as an example) plus selection that causes evolution and that process involves chance.
Explain how chance is involved. Do you mean that the event is entirely random?
The event is not entirely random. There are forces in play that cause a particular mutation to happen, but from the point of view of the individual animal, all of that stuff is invisible and the mutations appear to be random. We say that they are random with respect to fitness. The environment does not reach down into the cell and cause the mutation to happen (there are exceptions to this that are unimportant to this point), so from the point of view of the environment (where the selective pressure happens) the mutation is random, or a result of chance.
Chance does not cause anything. Chance is a term to describe the fact that from where you are standing, and despite the fact that there are underlying rules that govern how the even unfolds, the event cannot be predicted from the data that you have and also that a reproduction of that event given actually random inputs will behave in the same way as the naturally occurring event.