According to MSDN the System.Windows.Controls.Calendar
does only support the Gregorian calendar - so basically doing what you want is impossible using the built-in control...
You will need to build such a control yourself or buy some control pack with Hijri support...
For some information on dealing with Hijri dates in .NET see MSDN.
EDIT:
The only calendar controls supporting Hijri I could find are here and here and here.
The "bigger" vendors in the .NET control world (like Telerik, DevExpress...) do NOT support hijri... they all have some "issue tracking" saying that they will look into adding support but these issues are open for years without any progress so far :-(