Some wireless earbuds can fall out when running, but the key is to find a pair that has a secure fit. Many earbuds are adjustable—they come with different size silicone tips for different size ears.  The earbuds should be fully inserted into your ear so the silicone forms a tight seal with the walls of your ear canal. Making sure they fit correctly, and choosing a pair with ear hooks, will lessen the risk that you’ll lose them on your run.