This isn't about hacking the game, but rather "cracking" the entity's behavior logic. By using the Piston Trap mentioned above, you effectively override Mal0's teleportation or despawn triggers.
Is the already following you, or are you trying to find it? lovely craft piston trap how to get mal0 cracked
Keep the entity rendered in one spot without it vanishing. This isn't about hacking the game, but rather