Common signs of a mouse infestation include:

.Scattered droppings: Mouse droppings are small dark pellets (smaller than a grain of rice) and usually scattered in large numbers. Usual places to find them are in loft spaces, kitchen cupboards and under kitchen units. 
. Damage to stock and property: With continually growing incisors, mice need to gnaw to stop them growing too long. This results in damage to a variety of materials including soft metals. Food left in packaging also becomes short work to feed on.
.Scratching noises: Mice can gain entry into a property through various ingress points. Once inside, they will gain entry into wall cavities and roof spaces. Movement on the plasterboard walls and ceilings can make even the smallest of mice seem much bigger!