Yes, the Morph can be used as a simple sketchpad with No Overlay or the Innovator's Overlay.
To put the Morph in the correct mode, you will need to create a No Overlay or Innovator's Overlay, select or create an area that takes up the entire sensor area, and then change it to be a Stylus or Paintbrush Area (found under Touchpad Areas in the dropdown menu in the SenselApp).
For Stylus Area: With No Overlay, a soft tip stylus should be used. With the Innovator's Overlay a firmer stylus can be used.
For Paintbrush Area: Fingers or a stiff paintbrush can be used. It is best in the No Overlay mode. The Morph is naively compatible with Windows Ink (which is used by many applications including the latest Adobe products like Photoshop and Illustrator). On macOS, we have a driver that works on macOS version 10.9 to 10.12.