I would use Meters
meters
A door is about 2 meters, but most likely you'd measure in centimeters.
While the dog is standing up on all fours, measure from the floor to the top of the shoulder.
milimetersMilliliter
kilometers
You would have to be able to get to the top of the flagpole, so I would say that the answer is "with some difficulty". It also depends on characteristic (mass, volume, radius, height) what you wished to measure.
The metric unit commonly used to measure height is the meter. So, you would measure the height of Big Ben in meters.
You would use meters.
millimetres (centimetres could also be used)
meters
Centimeters would do it. A doorknob should be 91 centimeters (3 feet) above the floor.
It depends on the relative height of the flagpole. If it's short, like a flag mast on a boat or building, probably feet and inches would do. If it's very tall, like the flagpole on top of a building or monument, yards and feet might be more appropriate.
6 m would be used to measure flagpole. 600 m is a bigger unit.
A door is about 2 meters, but most likely you'd measure in centimeters.
Metres (American spelling = meters), unit symbol "m", would be the most appropriate metric unit to measure the height of a 32-story building.
To measure the height of your school, you would typically use meters, as it is the standard unit of measurement for height in the metric system. For smaller measurements, centimeters could also be used, but meters would provide a clearer understanding of the overall height.
The height of a building is measured in metres.