If you already own a physical copy (like a DVD or Blu-ray) and want to extract the audio to use with a different player, you can use legal tools like the VLC Media Player to "Convert/Save" the video file into an profile. This allows you to have the Hindi audio for personal use without downloading from unverified sources.
Searching for "Mp3 Download" of an audio track typically leads to several risks: Avengers Infinity War Hindi Audio Track-- Download Mp3