Someone hanging around the house at night.

My parents live out the country side, theres a few houses dotted around the area but mostly surrounded by fields.
A couple of times over the years ive heard noises outside the house, like footsteps, things being dragged/moved and noises in the shed. Id usually put noises outside down to wildlife or wind but some times the noise has been so obvious the only explanation is someone outside.

This morning at about 4.30 I went down stairs to use the bathroom. The bathroom is an extension part of the house, outside along the bathroom/extension is a long narrow path with an old wooden gate that leads onto a patio. While in the bathroom I clearly heard someone running down the narrow path, push past the gate and run around the extension onto the patio which leads onto the side of the house. Then the noise stopped.
There is no clear view onto the patio from any window in the house so although I looked out and saw nothing, I cant see the whole area.
I thought I heard a noise earlier in the night and went down to make sure the back door was locked as my parents have a habit of forgetting to lock it but walking past windows in the house I got a chill and feeling of being watched.
Allot of the windows down stairs are quite big with no curtains or very light net curtains so if someone was outside, they can see right in but because its dark, I cant see out.

A few weeks ago I heard noises like mams ceramic flower pots beside the front door being dragged. - Its directly under my bedroom - its a two story house.

Nothing ever seems to be missing from outside the house and there never seems to be any attempt by who ever this is to get inside the house.

Im just wondering if anyone has experienced anything similar? What could they be doing? and is there anyway from stopping it from happening?

While typing I can hear a bit of banging coming from the back of the house.