I'm a little unclear what you're asking but if I understand correctly you want to extract point measurements for hydraulic head like you would get from a piezometer. If you have assigned the location of your piezometer screen as a supermesh point when you constructed or as an observation point its easy. With the hydraulic head selection activated in the process variable tab, click on the node you are interested in. Then right click on Hydraulic Head and export data. This is good if you're running in transient mode. If you're in steady state just use the inspector tool to look at the node location you're interested in.
