I use a wet erase battle-mat. I will draw out rooms as they explore in 10' square scale (which helps the mapper out).
I bought a big pack of Arcknight plastic miniatures. When a player joins my game, I'll let them pick an appropriate plastic mini and I let them just keep it. They're pretty cheap and the time it saves from having to hunt for a mini is way more valuable to me.
If a fight breaks out, I'll sometimes redraw the room in 5' square scale, but not always. I use minis as positional tools not precise playing pieces. I just need to be able to know if a PC can move and attack or how many foes can be struck by a fireball. I don't care about every 5' of movement.
With 5E, some of my players use their laptops and/or phones. I personally dislike it, but I don't make a big deal out of it.
I usually either run from a printed out module or from my own own notes that are hand written... I can't run off of PDFs. With 5E, I use my laptop with D&D Beyond open for reference and monsters stats. When I'm running Basic, I don't need the computer, I can handle monster stats from the book or from memory.