Altium PCB layout: Measure points
In altium, the heads up display shows the dx and dy from wherever you last clicked. Show the heads up display with Shift+H.

It has something called hotspot snap where it attempts to guess the thing you are interested in when clicking, for calculating the hotspot origin. Ie if you click on a via 1 mil off the center, it will think that you actually want the via itself and will set the hotspot origin at the exact center of it.

If you want more precise measurements then you'll need to either move the origin or jot down the locations of things and do the math.

There are also some other options you can play with in View > Board Insight