To make the ball fly, you need to fill it with gas. To create gas at home, you need a chemical reaction of water, aluminum and caustic soda. With water and aluminum, everything is clear, tap water and baking foil are suitable for us. The third link in the reaction will be a pipe cleaner containing sodium hydroxide (read the composition).
The volatile gas released during the reaction lifts the ball into the air. Be very careful when mixing the ingredients, such experiments must be carried out in the presence of adults.