Andrew Marvell's poem "The Garden" speaks to the idea that many people may only look to one area in life which they try to excel in. The speaker, on the other hand, seems to wish that people tended not to be so close-minded. Instead, the speaker suggests that one should look to nature to find true happiness.
That being said, the displacement which exists in the poem can be found in two different ways. First, given the speaker's stand, it seems that people are far too preoccupied with success (which can bring happiness) than happiness itself. Secondly, the displacement can be identified as the feeling one may get with surroundings which they are not comfortable in (like a garden).
The second idea supports the age old conflict between man and nature. Some of mankind may not be comfortable in nature--they simply cannot find the peace and solace with it as the speaker can.
Essentially, the displacement is underlying. The poem, itself, is meant to show the problems associated with striving for something which cannot bring spiritual transcendence or true happiness. The displacement, then, must be inferred by the reader given the poem states what one must do and not how one is out of place. In a sense, the poem tells readers where to be in order to be happy and in the right place.