How to add cash from cash app to apple cash

I am not sure you can. Add money to Apple Cash - Apple Support

In settings click on wallet. Select Apple Cash. Link your debit card. Once linked, click on add funds and type in the amount (min of $10) and voila! It will charge your debit card and add it to your Apple Cash. But heads up, you cannot make in-app purchases using Apple cash. Hope this helps :)

There's no way to add cash from Cash App to Apple Cash directly.

But you can use the same debit card for both Cash App and Apple Cash.

Hope this helps.