Since rodents are nocturnal you’ll rarely see them during the day, so look for signs of their presence:
If using indoors, simply place a 500g jar near any suspected entry points (doors, cracks, next to the wall, etc.) and remove the lid. One 500g jar is effective over a 100 square feet area.
For preventative use over larger outdoor areas, use the 9kg jug to pour a continuous line of Hightail (approx. 5cm wide by 2cm deep) around the perimeter of your building creating a rodent-free barrier.