Just a little above me, he was fighting with all his might.
On the summit of the mountain, he cried with joy.
These are sentences with Locative Adjuncts. A Locative Adjunct is an Adjunct (read "adverbial") which gives you more information about where something was or where it took place. ThThe majority of Locative Adjuncts in English are preposition phrases (this just means phrases headed by a preposition). These Locative Adjuncts have been preposed, moved to the beginning of the sentence.
In sentence (1) the Adjunct is headed by the preposition above. This preposition has a complement, the word me. It isn't the first word of the phrase because it is being modified by a measure phrase just a little.
In the second sentence the preposition phrase is headed by the preposition on. Its complement is the summit of the mountain.
Notice that in both cases these adjuncts could also go after the sentence, instead of before it. This is a common feature of proposition phrase Adjuncts, especially locative ones:
He was fighting with all his might just a little above me.
He cried with joy on the summit of the mountain.