Use /testfor to make a custom command

You can't test exactly for /f map, but you can do similar with /triggers.

First, set up the trigger objective:

/scoreboard objectives add fmap trigger

Then, when people type:

/trigger fmap set 1

You can select them with @a[score_fmap_min=1], or tell them something like:

/tellraw @a[score_fmap_min=1] {"text":"message"}

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As a side note, creating a faction plugin with command blocks is a very ambitious goal, may be worth starting off with something simpler and smaller.