There are studies indicating that traditional pen and paper note taking is better for knowledge retention and understanding. To back-up handwritten notes, it is a good idea to digitize them and there are different notebooks designed for this purpose.
Moleskine and Leuchtturm both sell notebooks optimised for digitisation. Moleskine collaborated with Evernote to produce a 'smart' notebook. The notebook's paper has dotted lines that are optimised for scanning via a smartphone/tablet camera. After scanning, content is enhanced for OCR to enable searching handwritten notes in Evernote. The notebook also includes stickers that can be pre-set, within Evernote, to tag scanned documents or to send notes to certain notebooks.
Leuchtturm utilises Whitelines paper that is designed to work with the Whitelines Android/iOS application. Similar to Moleskine's 'smart' notebook, Whitelines paper makes lines disappear and notes standout after scanning. The lines, in this case, are white and the background grey, with four corner markers that auto-detect the page selected for scanning. At the bottom of the page, there are three squares that can be ticked to send the document to an email, Evernote and Dropbox. In the application, it is possible to set destination preferences for each of these options.
I prefer Whitelines paper to Moleskine's Evernote notebook, as the latter is tightly integrated to work within the Evernote app; Whitelines, in contrast, is platform neutral. The results of scanning can vary but Whitelines, from experience, consistently produces better results. Further, it is not necessary to purchase a Leuchtturm notebook to use Whitelines paper, as Whitelines produce their own notebooks that can be purchased in different formats and sizes.
Rocketbook notebooks perform a similar function to the Evernote smart notebook and Leuchtturm’s Whitelines Link notebooks. The difference is that Rocketbook sells re-usable notebooks. The Rocketbook Wave can be erased using microwave heat and re-used up to five times. The Rocketbook Everlast is marketed as “endlessly reusable”; the notebook's pages can be wiped clean using a damp cloth. The Pilot FriXion pen is required to re-use both notebooks. To test Rocketbook’s scannable paper there are PDF downloads here - to get the best result, the sheets should be used with the Rocketbook app.
A final point: handwritten notes, in a regular notebook, can be uploaded to the cloud with a designated scanning app and some of these apps support OCR too. The paper, in these notebooks, may not be optimised for digitization but often, from experience, I found the difference in results negligible (one issue to consider is that lines, in lined notebooks, remain after scanning a document). I regularly use Adobe Scan but there are other applications.