You can Zap profiles on iOS but it’s against their guidelines to Zap notes as they consider it tipping digital content.

You can use https://www.zapplepay.com/ if using Alby which once setup and linked to your wallet will turn your reactions into zaps.

https://www.zapr.social (I built and use) is an alternative which allows you to zap any amount without being bound by reactions or linked to your wallet in anyway. Zaps works with a number of wallets you have on your device.