If you don’t mind wearing something underneath the skirt you can the these yoga pants/ leggings that have phone pockets
High Waist Yoga Pants with Pockets for Women - Soft Tummy Control 4 Way Stretch Leggings for Workout Running https://www.amazon.com/dp/B08H7X1VBT/ref=cm_sw_r_cp_api_glt_fabc_21J66DPJVWYCH80SW422?_encoding=UTF8&psc=1