Need to check if specific number is part of a string

I have a string in cell A1, such as "asdfk1234jh", and cell B1 contains the number "1234". I want to determine if the exact number in B1 is present within the string in A1. Existing solutions only return "TRUE" if any part of the number is found, like "12" or "123", but I require a formula to confirm if "1234" specifically exists in A1.