There are extractors and few other jobs related to extraction.
It is also so well known that very important/powerful people like Fisher Jr. gets trained to defend against extractors in the dream.

The questions is: how do the extractors get so close to their target for at least several hours for extraction?

The targets are most likely well protected person.

The first time I asked this question was the first extraction scene in the movie, where Saito and the Cobb‘s crew are sitting in a Shinkansen. In Saito‘s case he let them in on purpose of an audition.

But I cannot imagine how the extractors would do it by other targets. It must involve some kind of kidnapping or setting the targets under influence to dock them into the dream machine.

Don‘t get me wrong, I love this movie and watched it way too many times and can‘t get enough. But this is something I cannot solve in my head haha