Thanks for the suggestion, Michael. I knew about these others but wanted to keep it simple for the moment.
Actually, with some more diddling around I found that if you tap to place the insertion point in a block of text in Notes, then touch the squiggle in the upper right corner of the keyboard that appears, you get a blank page. If you draw on this page with finger or Pencil, then tap Done, the text returns with the drawing placed in a gap in the text beginning where the insertion point had been. Tapping alongside the drawing returns you to the drawing page, where you can erase or modify the drawing, then tap Done again. If you've erased the drawing, you have a gap in the text to backspace out.
I haven't figured out how to do the opposite: Bring up the keyboard to add typed text to a drawing.