export a pdf with comments from indesign

Kerntiff Publishing solutions has a paid script that will convert note to speech bubble comments upon export: https://www.kerntiff.co.uk/products-4-indesign/pdfstickies

This is also something that other users have requested. If this is imporant to you, make it known to the developers by voting here: https://indesign.uservoice.com/forums/601021-adobe-indesign-feature-requests/suggestions/35793727-export-pdf-comments

The Notes tool can embed notes within text in textframes (a concept borrowed from InCopy and Word).

Many designers choose to make a layer, set it to non-printing, and put textframes of notes on that layer. These notes could be on the page or the pasteboard. Once exported as a PDF, viewers can read the notes. 

Make sure to train your Acrobat users that they should use only the 3 auto-edit commenting tools so that you can simply "Accept" them back into the layout text for faster text editing.