Inches (or centimeters, if you're working in the metric system).
You should clarify what you want to measure about it: its diameter, mass, weight, color, etc. If you want to measure its diameter, that would usually be specified in microns (= micrometers).
Meter.... or more likely millimeters
Metric ruler
The number of the pencil is based on the type of carbon lead used inside. The thicker the carbon lead gets the higher the number of the pencil becomes. If you notice a mechanical pencil is 0.9mm in diameter so it would be called a #0.9 pencil. A #2 pencil's lead is 2mm in diameter. So Why would we call a pencil a #3 pencil? Because it's lead is 3mm in diameter.
An average pencil when new would be around 15 centimetres long.
The metric unit used to measure the mass of a pencil would be grams (g).
Micrometer
milimetersMilliliter
to be honest I would use a metre ruler that really helps a lot place your metre ruler on your desk. put your pencil starting from 0. Then measure it. This is how you would measure it.
Inches (or centimeters, if you're working in the metric system).
You should clarify what you want to measure about it: its diameter, mass, weight, color, etc. If you want to measure its diameter, that would usually be specified in microns (= micrometers).
Meter.... or more likely millimeters
You could use either centimeters or millimeters, but probably centimeters.
An appropriate metric unit of mass for a pencil would be grams.
Metric ruler
The width of a standard pencil is typically around 7 millimeters.