Don't want to write this by hand? GodCraft sets minecraft:suspect_tracking for you with a switch.Get GodCraftOverview
minecraft:suspect_tracking is an entity component: it goes in the components object of a custom mob, or in one of its component groups. Lets the entity remember where it last noticed something suspicious, like the warden tracking a sound.
Example
Inside the components object of BP/entities/<name>.json (values are the defaults or placeholders):
BP/entities/<name>.json
{
"minecraft:suspect_tracking": {}
}