Monarch works with the text content of a PDF file. Adobe's text conversion does something similar.
In both cases any graphics and images in the file will not be converted to text, as you would expect.
When you scan a document the result is a graphic file, not text. So the scanned document cannot be converted directly to text.
It may be possible to run the document through an OCR (Optical Character Recognition) application to produce a useful output as text. By useful I mean an output that has enough accuracy to make the exercise worth the effort AND very little chance (preferably no chance) of any of the critical characters being wrongly interpreted during the process and not corrected by review after interpretation.