Extracting Certain Numbers From String

I have not managed to find exactly what I am looking for so far..

I have cells with a mix of numbers and strings and I would like to extract certain numbers only.

I.E.
123a bcd8
acbd 1234e

I would like to only extract the first instance of numbers - so in example 1 - 123 and in example 2 - 1234. I have found various methods of extracting all numbers such as:

Function ExtractNums(r As String) As String
'Creates and returns a reference for a regular expression object
With CreateObject("vbscript.regexp")
'Sets the pattern to be non-digits
.Pattern = "D"
'We want to find all matching non-digits
.Global = True
'Replace all non-digits with an empty string and return this value for the function
ExtractNums = .Replace(r, "")
End With
End Function