If you're okay with modding your controller, this seems to do exactly what you want:

https://www.amazon.com/Playstation-Dualshock-Board-Remap-Install-4/dp/B00SVHWMEQ

SCUF made an external adapter but I don't think it's manufactured anymore:

https://www.amazon.com/Collective-Dominator-Controller-Adapter-playstation-4/dp/B01L8QHXJA