You can read and write data as binary very easily:
Dim data As Byte() = File.ReadAllBytes(path)
...
File.WriteAllBytes(path, data)
The problem is converting it to a string requires a little more knowledge: specifically the format of the data you are reading and the format you want to use as a string. Bytes are 8 bit hex values, but strings are made of characters - which are 16 bit Unicode values for the most part, and it may not just be a case of "read bytes, treat as characters" - the results you get as a string or text file may not be what you expect, or even readable.
Do you have any idea what the binary data is? And how you want to store it?