The idea is having a shape. When the cursor hovers and then moves away from the shape, part of the circle stretches towards the shape before moving back.

Steps:

• First the cursor can hover over the shape and nothing happens
• If it leaves the shape the edge of the shape stretches towards the cursor
• If cursor is far enough away the edge of she shape snaps back
• If you hover over the circle again, the same thing will happen

Cursor moving in and out of shape example