What's the best way to clean carpeted stairs?

Use strips of masking tape to pick up the loose pieces

https://www.doityourself.com/stry/how-to-maintain-the-carpet-on-your-staircase

Call and have profesionally steam cleaned.

Steps are a backbreaker to clean, especially if more than 2-3 steps. Call professional carpet cleaners and let them do the lugging around of hoses.

Use a clothing lint roller to pick up any surface type dirt. If wanting to actually clean the carpet you an get a tank type sprayer and liquid carpet cleaner. Start at top and work your way down. Spray 2 or 3 steps of carpet according to directions on cleaner. Use a small wet/dry shop vac that can sit on the steps to vacuum up moisture. Move to the next 2/3 steps.

Thank you to everyone. Unfortunately there are 13 steps and I think I will have to end up having them professionally cleaned UGH!