These two verses are generally understood as being together in one composite wise saying. In actuality, it’s three statements about negative behaviors and thoughts.
The first discusses someone who “plots evil.” Of course, that would not be good, and it is not surprising they would unflatteringly be “known as a schemer.”
The second statement continues the concept of “schemes” and relates it to both “folly” and “sin.” Most of us agree that scheming, evil, folly and sin should be considered together; and that they are not good!
The third statement isn’t so clearly associated with the first two, except that it also speaks of a negative attitude and behavior – the “mocker” who “people detest.”
In these verses, plotting and scheming bad things is a major issue. Not the doing of things – actions – but planning them.
As for the “mocker,” while certainly related to words and actions, it also represents a negative attitude and way of thinking.
Over and over the Bible focuses much more on our attitudes than on our actions. The key to human behavior is not what we do, but how we think!
Change that and we’ll change the world!