Start in the room the enclosure stands in
A dwarf hamster out of his enclosure almost always stays closer than owners fear, because a tiny prey animal moves along walls and dives into the first dark, tight cover rather than crossing open floor. Close the door of the room the cage stands in before you shift any furniture, so your searching cannot push him further through the house. Then work slowly around the edges of that room by torchlight: inside shoes and boots, behind the fridge or washing machine where motor warmth draws him, under sofas, inside recliner mechanisms, and along the warm side of pipes and radiators.
Think like a hamster while you search
Dwarf hamsters can flatten through gaps barely wider than their skull, so check behind kickboards, inside cupboard backs with pipe holes, and under doors with generous clearance. Listen as much as look: pause, turn off background noise, and wait for the faint rustle of bedding-like material being rearranged or seeds being pouched. Sprinkle a light dusting of flour across doorways and in front of likely hideouts in the evening, and in the morning the tiny tracks will tell you which room and even which corner he is actually using.
Set a trap he walks into himself
Chasing and grabbing rarely works and risks injuring a very small animal, so let hunger bring him to you. Place his own cage, door open and stocked with familiar bedding and food, on the floor beside the suspected hideout, or set a humane live trap, or a bucket with books as a ramp and bedding and seeds in the bottom that he can drop into but not climb out of. Count out a small pile of sunflower seeds near each trap in the evening; a pile gone by morning confirms he is visiting even if the trap itself needs adjusting for another night.
Protect him while he is still loose
Until he is caught, keep cats and dogs shut entirely out of the search rooms, warn everyone in the house to watch every step and check chairs, cushions, and laundry piles before sitting or washing, and leave exterior doors opening only through another closed door. Put down no snap traps or poisons anywhere in the house during the search, and avoid moving heavy appliances blindly, since he may be asleep directly behind one. Keep a shallow bottle cap of water in each likely room so a hamster out for several nights does not dehydrate before he finds the food traps.
Organising the household search
An escaped hamster search fails most often through duplication: two people move the same sofa twice, nobody checks the flour in the morning, and a sighting mentioned in passing is forgotten by evening. Give each room an owner, write down where traps sit, and keep every sighting, footprint photo, and seed count in one shared thread instead of scattered conversations — KinsLe Messenger keeps every conversation about a pet in one per-pet communications hub, so the family searching for your hamster, anyone who spots him, and whoever checks the traps are all working from the same running account of the hunt.