The First Order is actively hunting for Luke Skywalker, in order to kill him.
From the opening crawl:
In his absence, the sinister FIRST ORDER has risen from the ashes of the Empire and will not rest until Skywalker, the last Jedi, has been destroyed.
Leia is seeking Luke to enlist his aid to restore peace and justice to the galaxy. Again, from the opening crawl:
With the support of the REPUBLIC, General Leia Organa leads a brave RESISTANCE. She is desperate to find her brother, Luke, and gain his help in restoring peace and justice to the galaxy.
Leia believes that without Luke, the Resistance is doomed. From the novelization:
“We’re still at war with First Order,” Leia pointed out. “A war that won’t end until either it or the Resistance is destroyed. The next time, without Luke, we won’t stand a chance.”
Snoke wants to destroy both the Resistance and the Jedi:
“There is no need for concern.” Despite the Supreme Leader’s cautioning, Ren’s assurance remained unbounded. “Together we will destroy the Resistance— and the last Jedi.”
Finn explains that the First Order will kill anyone who gets in their way of the map.
Finn nodded and indicated BB-8. “It’s the map he’s storing. The First Order wants it, and they’ll kill anyone who tries to keep it from them.”
Luke isn't specifically hiding from the First Order, he's hiding from everyone.
He turned to the others. “This is accurate, but it’s not complete. It’s just a piece. I can tell from the location of the breaks and from what’s only partially shown.” He grunted softly. “Ever since Luke disappeared, people have been looking for him.”
Rey spoke while drinking in the details of the marvelous but imperfect chart. “Why’d he leave, anyway?”
Han pursed his lips; thinking back, remembering.
“He was training a new generation of Jedi. There was no one else left to do it, so he took the burden on himself. Everything was going good, until one boy, an apprentice, turned against him and destroyed it all. Everything Luke had worked toward: gone. Luke felt responsible. He walked away from everything.”