Just copy and paste in VBA Editor:
Function RegExpFind(text_string As String, pattern As String) As String
Dim regEx As Object
Set regEx = CreateObject("VBScript.RegExp")
With regEx
.Pattern = pattern
.IgnoreCase = True
.Global = False
End With
If regEx.Test(text_string) Then
RegExpFind = regEx.Execute(text_string)(0)
Else
RegExpFind = ""
End If
End Function
Sample usage:
=RegExpFind(A1;"[\d.]+x[\d.]+")