Tracing
From GeoGebra Manual
Objects can leave a trace in the Graphics View when they are moved. Use the Context Menu to switch this File:Trace on.gif Trace On. Then, modify the construction so that the object whose trace you turned on changes its position and leaves a trace.
Note: You can turn off the trace of an object by un-checking Trace On in the Context Menu. The menu item view-refresh Refresh Views in the View Menu clears all traces.
Note: The trace is not permanent, it disappears e.g. on zoom. Instead of permanent trace of a point you can use Locus.
Tracing to Spreadsheet
Right-click on a Point in the Graphics View -> Trace to spreadsheet option