I am only aware of payed versions and they are quite expensive.
I use PDFtoMysic by Myriad Software. There are also a PRO version. The basic version can export to MIDI and the PRO version can export to both MusicXML and MIDI. Note that it only works for music that have been written to PDF by a Music score editor (i.e. not scanned PDFs).

If you only have one song to export from PDF to MusicXML or MIDI maybe you can try their trail versions. Just download the software and it is in a trail version.

The trial version allows you to export one page only at the time from the PDF (but as far as I can see when I testing it it is possible to go through the pages and export them one by one, I just tested with a few pages). If it works the result will be a series of Music XML pages (if using the PRO trial) building up to the complete score.

So some editing to merge it all together will be necessary in the end.

PDFtoMusic link

I am not aware of any software that can convert scanned versions of PDF music scores. The few versions I have tested in the past just ended up with rubbish results just takes up lot of time trying or editing.