Despite the perk description only mentioning weapons and armor, it also allows additional materials to be salvaged from scrapped settlement objects. For instance, a baseball player statue that requires 10 copper to build normally yields nothing when scrapped, but having rank 1 of this perk allows the player to salvage 2 copper from it, and having rank 3 increases the yield to 5 copper.
Modified weapons will produce additional components
Certain mods and prefixes indicate whether some components may be scrapped from them, while other components are linked to the base weapon. For instance, weapons with the "muzzled" or "silenced" prefix will nearly always yield aluminum (though the quantity depends on the base weapon), while wood and copper are tied to the base weapon (double barrel and combat shotguns and hunting rifles in the case of wood, and pipe weapons for copper), with the modifications determining the quantity. Unlike other resources, wood is often present with less technical mods, with the "short" versions often providing the most.
The same applies to armor, but the effect is less dramatic (significantly less-common modifications are needed to extract the more uncommon/rare components).
The highlighting effect from rank 2 applies to junk and containers containing junk with components that have been marked for search only, not to weapons and armor.
Obtain more components when you scrap weapons and armor.
Unlike the Fallout 4 version, the perk does not allow additional resource types to be recovered, instead it increases the amount of resources gained. Common resources increased in this manner are Steel, Molded plastic and Wood. In some cases the bonus is up to 3x the amount.
Additional resource types from equipped mods (eg. glass from scopes) does not require the Scrapper perk.
The perk applies its bonus in addition to bonus resource gain from the player character's Intelligence stat.
An example of the interaction between Intelligence and Scrapper follows in the table below, for scrapping a Short Assault Rifle.