Much later, Mjolnir was bequeathed to his son Thor, after he proved himself worthy through several trials.  With few exceptions, Thor has carried Mjolnir throughout his adventures. Thus, the history of Mjolnir follows that of Thor. Although Asgard was destroyed in Ragnarök , Thor and the hammer, survived. 
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That idea of worthiness would often come back around in the comics as any time Thor was deemed unworthy arrogant and selfish he would no longer have access to his hammer, much like the character’s first film in the Marvel Cinematic Universe.
While not true for the regular continuity in Marvel comics, in the Ultimate Universe, Mjolnir actually has a piece of Asgard hidden inside the hammer to help give birth to a new realm in the event of Ragnarok.
Ages ago, an unimaginably powerful cosmic storm called the God Tempest approached Asgard. Odin , chief of the Norse gods, battled the storm for many days when it threatened Asgard. Once the storm was weakened enough, Odin defeated the God Tempest by trapping it into a chunk of Uru that had been given to him by the Dwarves of Nidavellir as a gift. 
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Odin used a powerful piece of metal against the storm, holding it up, and watching as the metal absorbed the storm, trapping it inside. It remained trapped inside the piece of metal, and the metal was eventually used to forge the hammer.
As Lord of Asgard, Thor possessed the Odinforce, which enabled him to tap into the near-infinite resources of cosmic and mystical energies, enhancing all of his abilities. With the vast magical power of the Odinforce, Thor was even able to dent Captain America’s virtually indestructible shield with Mjolnir.
Once a worthy individual has become the one to hold the power of Thor, Mjolnir recognizes them as master and never wants to be separated for long. The hammer’s will to be with its master is so strong that nothing can stop it from returning to them.More pictures: «Hammer of thor vs klg express».