Where is my voice to text button?

Your voice to text button is the microphone icon on your keyboard. On iPhone it sits at the bottom right of the keyboard. On Android with Gboard it is in the top toolbar, and on Samsung Keyboard it lives on the toolbar or behind the comma key on some layouts.

The button only appears while the keyboard is open, so tap into a text field first.

If the mic is missing, voice input got disabled. On iPhone, re-enable it under Settings, General, Keyboard, Enable Dictation. On Android, open your keyboard's settings and turn voice input back on. Language packs and mic permissions knock it out too.

A voice to text app puts a mic in every app so the button never hides again.