I've doodled on my hands notes during the exam, invigilators didn't seem to care but at the same time just doodle on the corner of the page, I know exams can be stressful and doodling can help relieve it, especially giving yourself a small break during an exam can help you maybe find a new train of thought for a question. Shame people replying didn't have the ability to unburrow their heads out their ass to give an actual answer.