Keep a list of tasks. I'm using Google Keep app for that, but a paper notepad and a pen will work as well.
It's not something groundbreaking, it will only help to keep your work organized, and you need to make a habit to look at your task list.
Came to your desk? Look at your task list, start working on rhe first item.
Phone call? Write it down into your task list and forget about whatever they wanted from you. Pick up the first task on your list, keep working on it.
Some coworker came to your desk and wants something done? Write it down to your task list as the second item from the top, show it to them that you will work on their request immediately after you finish your current task. Your direct manager gets the top spot in your list, everyone else will have to wait until you finish your current task, because working on two things in parallel will take you four times longer (if you finish it at all).
Need to replace the lightbulb in the room? After you finished that, you got the bright idea to buy brighter lightbulbs for every room. Stop. Write it down into your task list, somewhere near the end. Pick up the task on top of your list, and keep working on it.
That technique won't help with procrastination sadly.