How to do Hand-Writing to Text on the digital keyboard?

I Was on the Google Translate app while on my iPad Mini 4. I fond that there is a button on the keyboard I had not seen before. After tapping it, I found it was one of those features that turn what you write with your finger or stylus Into text. I really like this feature and it has been very helpful to me.... However, I want to be able to do so on my other apps aswell.

SO the Question is: How do I get the Handwriting to Text feature to work on other Apps, or just on the keyboard in general?

Thanks,

-Brady V.