All you really need is a pencil- or just anything you can draw with. Markers, pencils, etc. there really isn't anything you especially need. Doodling is what people do when they're bored.
Just pick up a pencil and draw... If there's a lack of inspiration, look around you for ideas.
I generally draw really quick sketch-things of people and eyes and random stuff like that...
They aren't the best, but I like doodling them anyways.
thank you for watching, enjoy doodling!