In my question on silent e, ctype.h's answer includes this:
A silent e is often employed to modify the pronunciation of the preceding vowel, functioning much like a diacritic would in many other languages.
I know people are employed by companies, but can a silent letter be employed?
Yes. "employed" or rather "employ" as a verb has effectively the same meaning as "to use" or "to make use of", but with a connotation towards the item not being consumed in the process.
Obviously the major use of the word employ is in the sentences like
I employ two members of staff
In this case, both members of staff would be referred to as employees and I would be their employer, however it is entirely valid to use it in other contexts where an item (particularly an intangible one) is used:
I was losing my game of Chess with Kasperov until I employed the Queens-Rook defence.
We employed a new technique to defeating our competitors last week.
I wrote a strongly worded letter to the CEO last week, in which I employed some decidedly untactful remarks.
