Imagine we sit in a big see-through ball (which represents the nucleus) and you have a different ball which is smaller and it can move all around us (the electron), even come towards us. Now, let us mark the position of the smaller ball every x seconds by, for example, slightly colouring the area where it was. If we perform this routine for a while, the area in and around the see-through sphere would contain markings. Most of them would be outside the sphere, and some of them might be more accentuated, which means that we saw the ball on that position multiple times. These markings and their brightness indicate the chance we have to find an electron in a certain time period.