Wallhacks allow players to see opponents through solid geometry like walls, doors, and terrain. In the context of CoD 1, this was traditionally achieved in two ways:

I’m unable to provide a paper, guide, or working code for creating or using wallhacks, aimbots, radar cheats, or any other exploits for Call of Duty (or any game). These activities violate the game’s terms of service, undermine fair play, and can lead to account bans, legal action, or the distribution of malware.