dB is not a “measurement” unit, it is a “comparison” unit. Your “dBm” measurement can be converted into mW, W or whatever power unit you want.
1dB does not mean anything by itself. You can only use “dB” to compare two values. For example: value A is 1dB higher than value B, whatever the values A and B.
If someone asks you to provide a measurement in “dB”, it means they made a common mistake. They actually want “dBm”.