I was wondering, since Dumbledore can hack the enchantments around Hogwarts so he can apparate and disapparate, then was it he who in the Order of the Phoenix (the fifth film) disapparated with Fawkes from Hogwarts, away from Fudge and Umbridge when they were in Dumbledore's office?
Fawkes got Dumbledore out of the office using phoenix magic.
It’s made clearer in the book that Fawkes was the one responsible for his and Dumbledore’s sudden disappearances. Dumbledore grabs onto Fawkes’s tail, then they disappear in a flash of fire.
“Fawkes circled the office and swooped low over him. Dumbledore released Harry, raised his hand and grasped the phoenix’s long golden tail. There was a flash of fire and the pair of them were gone.
‘Where is he?’ yelled Fudge, pushing himself up from the floor. ‘Where is he?”
- Harry Potter and the Order of the Phoenix, Chapter 27 (The Centaur and the Sneak)
Dumbledore does control the enchantment on Hogwarts that prevents wizards from being able to Apparate and Disapparate there, so he could easily lift it temporarily to let himself Apparate or Disapparate.
“As you may know, it is usually impossible to Apparate or Disapparate within Hogwarts. The Headmaster has lifted this enchantment, purely within the Great Hall, for one hour, so as to enable you to practise. May I emphasise that you will not be able to Apparate outside the walls of this Hall, and that you would be unwise to try.”
- Harry Potter and the Half-Blood Prince, Chapter 18 (Birthday Surprises)
However, despite it being possible that Dumbledore could Apparate while within Hogwarts, this isn’t what happened when he and Fawkes escaped from Fudge.
Apparition doesn’t have a flash of fire when a wizard Disapparates, there’s just a pop and they’re gone.
“With two loud cracks, Fred and George, Ron’s elder twin brothers, had materialised out of thin air in the middle of the room.”
- Harry Potter and the Order of the Phoenix, Chapter 5 (The Order of the Phoenix)
However, when a phoenix uses their power to disappear, there is a flash of fire.
“Dumbledore was now stroking Fawkes’s plumed golden head with one finger. The phoenix awoke immediately. He stretched his beautiful head high and observed Dumbledore through bright, dark eyes.
‘We will need,’ Dumbledore said very quietly to the bird, ‘a warning.’
There was a flash of fire and the phoenix had gone.”
- Harry Potter and the Order of the Phoenix, Chapter 22 (St Mungo’s Hospital for Magical Maladies and Injuries)
This proves that, while both Dumbledore and Fawkes can Apparate and Disapparate in Hogwarts, Fawkes was the one responsible for that specific disappearance away from Fudge and Umbridge.