yuntop 5 Pack Phone Tether Tab Cell Phone lanyard pad, Universal Phone Tether Tab Phone Lanyard Replacement Part Compatible with Most Smartphones (Black)

There are various tethers available on Amazon. I got a couple to use when I started kayaking. My favorite was this one that goes under your case and a loop comes out of the case's charging port slot. Then I used this lanyard to attach to the loop and attached the carabiner to my life jacket.