Get Value from DataGrid Cell (WPF)

I am looking for a way to read the value of allways one specific cell (Row:0, Column 2) in a DataGrid.

In WinForms it was very easy:

I am searching for hours now without finding anything usefull. It is important that I can choose values programatically, like in the way above, without preselections with mouse etc.

I hope someone knows an answer to that

Regards