The answer to 'wasp scratching sounds' is that the sounds are likely caused by wasps building a nest or searching for a nesting site. Wasps make scratching or scraping sounds as they chew on wood, paper, or other materials to gather nesting materials. This is a common behavior as wasps prepare to build a new nest or expand an existing one.
The sounds can be loud and persistent, especially if the nest is located in an attic, wall void, or other enclosed space near the home. Along with the scratching sounds, you may also see wasps flying around the outside of your home as they search for a suitable nesting location.