in .Net All Strings are Unicode

we also know that  ASCII Characters range is up-to 255 any thing above 255 will be Unicode so what we will do is we will just check each character value if it is above 255 then there is Unicode Characters

here is function which does that

Public Shared Function IsUnicode(ByVal s As String) As Boolean

Dim items As Char() = s.ToCharArray()
For i As Integer = 0 To items.Length – 1

If CUShort(AscW(items(i))) > 255 Then
Return True
End If

Next

Return False

End Function

use it like

if IsUnicode(“لعربي“) then

‘ is unicode

else

‘not unicode

end if