You've asked this question in the FileMaker Go section (FileMaker for iPhone, iPad), but this sounds like you want to use a regular computer with some kind of scanner. Is this correct?
What type of scannner? barcode? Magnetic strip? RF tags?
Any scanner that can function in "Keyboardemulation Mode" can easily be used with FileMaker Pro on a regular commputer. Almost all Barcode and MagStripe scanners function in this way. Radio frequency scanners probably do as well but I haven't worked with them. Just check the manufacturer's specs to confirm that they work in this mode before you settle on a specific piece of hardware.
If you search this forum for Scanner or bar code, you'll find a number of threads that discuss ways to integrate a scanner with FileMaker Pro.
After connecting your scanner and if needed using the manual to set up the proper scan and click sequence, put the cursor in a Filemaker field and click the scanner. It will act as a keyboard and insert the scan data in your field.
You have the option of what character it will end the scan with, tab and return are typical choices. Tab of course will move the cursor to the next field after the click. This seems best if you are going to do a lookup or run a trigger script on exit or modify.
You could thus script an inventory count or a purchase order from a book of barcodes by making the trigger script create a new record.