What is this insect seen in Northern Italy?
This looks like some kind of bagworm moth. Their larvae would use silk and plant debris to construct a protective case around themselves. It’s hard to tell the exact species unless you open up the case or wait for it to emerge as an adult moth.

There are species on pretty much every continent and definitely some in Northern Italy. You can check out a list of observations and photos here: https://www.inaturalist.org/taxa/61415-Psychidae