Unearth is an activated ability you use from your graveyard, not your hand. By paying the unearth cost, you return that creature to the battlefield, but it gains haste—so it can attack immediately—and you must exile it at the beginning of the next end step. If it would leave the battlefield any other way (dies, gets bounced), it simply goes there instead of being exiled.
The key nuance people miss: unearth doesn't "exile it at end of turn" unconditionally—it only exiles the creature if it's still on the battlefield. So if you sacrifice or flicker it before the end step, you dodge the exile entirely. Also, unearth can only be activated at sorcery speed from the graveyard.
In Commander, unearth shines for one-shot value: blink it, sacrifice it for value, or swing for damage before exiling. Pair it with sacrifice outlets to keep the creature permanently.