To see measurements on the canvas, open the Precision menu and tap Measure to “On”. You can tap the label to toggle it on/off.
 
A measurement tag is visible on screen either when you select a stroke, or for 5 seconds after drawing a stroke.
 
Tap the measurement label to “save” or “stick” it to the canvas. The dots on either side of the measurement will disappear to show it is saved. This works for measurements that are attached to strokes, imported images, objects and Shape Guides (before and after drawing).
 
Measurements attached to strokes will live update if the item it corresponds with is selected, scaled or sliced.
 
Measurement tags and floating measurements can be selected with the Item Picker (only) and moved, scaled, rotated or deleted.