The maid is making a (thinly) veiled reference to sex, which is why she rubs her bosom while she's thinking of it. Although the work of a maid is normally cleaning and other household duties, unofficially some maids also had another "job" -- keeping the master happy. "Implement" is another word for "tool", and I think (but I haven't read the book so I'm not sure) that this man's "tool" would be the "tool" he uses for sex -- his penis. (Am I allowed to say that in here?)
Judging by the way the maid speaks, it seems she rather enjoys this extra "work".
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