The answer to 'how did termite get in my house' is that termites can enter your home through small cracks and openings in the foundation, walls, or roofing. They are attracted to the cellulose in wood and can silently infest your home for years before you notice any signs of damage. Common entry points include expansion joints, cracks in the concrete, and openings around utility pipes or wires.
Termite infestations often start outside the home, with termites burrowing up from the ground or entering through cracks in the exterior. They can then travel through the walls and into the wooden structures of your home. Signs of a termite problem include mud tubes, wood damage, and discarded wings near windows or doors.