When using the "=" operator to compare strings, it depends on whether Option Compare is set to Binary or Text. If it is set to Binary, using "=" performs a case-sensitive comparison. If it is set to Text, "=" performs a case-insensitive comparison.
You can use String.Compare to perform either type of comparison regardless of the value of Option Compare. String.Compare(string1, string2, True) will perform a case-insensitive comparison and return zero if the two strings match, e.g.
String.Compare("HELLO", "hello", True)
would return zero. Change the third argument to False to perform a case-sensitive comparison. Do a help search on "string.compare" for the details of all overloads.