First of all, a number can be represented as Hex digits, or as Binary digits, but it cannot be both at the same time.
Basically, what you have is a string containing hex digits.
I don't know if this is the best way, but it should work:
  byte[] HexStringToBytes(string hex) { byte[] data = new byte[hex.Length /2]; int j = 0; for (int i = 0; i < hex.Length; i+=2) { data[ j ] = Convert.ToByte(hex.Substring(x, 2), 16); ++j; } return data; } 
