How can i find the font used in notes app on ipad pro with iOS 11.0.2?

It is Helvetica (even though it doesn't say), and the monospaced font (which definitely isn't Helvetica).

If you want to use different types of fonts in notes, you'll need to look in the iOS App Store for more comprehensive notes apps that are compatible with the Apple Pencil.

Here are a few I can recommend.

Notability

Good Notes

Note Plus

Note Shelf

Notes Writer

NotePad+ Pro

UPAD

Tap on Aa.

That doesn't actual tell you the type or name of font.

The font can't be changed to a different font, either.

The Apple notes app is a very basic and very limited notes app.