Stem mount handle bar adapter

[RobisaII]

I have a phone case that mounts into the stem cap, but I want it on the handlebar. Is there an adapter that you can put on a handlebar that allows you to mount stuff that goes into the stem cap? I am trying to solve an issue without having to purchase a new mount and case, thank you in advance and please excuse my problem

 

[dabac]

If it mounts into the stem cap I assume it uses an M6 screw to engage the star nut?
In which case a properly sized P-clamp should wrap around your bar and allow you to mount the holder there.