Download the managed solution from here
- Install the managed solution "Uploader" in your environment.
2. Open the form where you have your custom field (any entity with Notes setup available). If it is a new custom entity enable notes for it.
3. Select the field and change control to _fileUploader from the list and click ok.
a.
4. Now save and publish.
5. Navigate to Model drive app UI and open any record with the field control enabled above.
Look inside D365