Freehand Measurement
Flexible Dimension Creation: Line and Point Modes
You can create dimensions either by snapping to existing lines in the drawing or by placing additional points freehand. Holding the Option (Mac) / Alt (Windows) temporarily switches the tool from line-based measurement to point placement mode, allowing you to define custom points where no geometry exists.
In addition, point mode still respects snapping behavior, if your cursor is near an existing point such as a corner or endpoint, it will snap to that point automatically. This gives you the flexibility to either place precise freehand points or take advantage of nearby geometry for accuracy, all while staying in point mode.