Use Capture Coordinate carefully
The use of the Capture Coordinate will excite the user in search of a plugin to make his life simple and quick when he wants to extract the x, y coordinates of a point because this is an easy tool to use. However, if you jump straight into it and not learn the ropes first before you go into the ring, you might face a knock-out. Observe above that by just changing the CRS from WGS84 (EPSG4326) and WGS84/Pseudor Mercator (EPSG3857) the x,y coordinate differ eventhough they both deal with WGS 84. I do not know how much that differs but I would let a surveyor clarify that for me.