The answer to 'how did silverfish get in my house' is that silverfish are common household pests that can easily find their way indoors. Silverfish are attracted to damp, humid environments and feed on organic materials like paper, clothing, and glue. They often enter homes through cracks and crevices, or by hitching a ride on boxes, furniture, or other items brought inside.
Silverfish can be difficult to eliminate because they reproduce quickly and can hide in hard-to-reach areas. Some common signs of a silverfish infestation include seeing the insects themselves, finding their droppings, or noticing damage to paper goods, books, or fabrics in your home.