smallest computer memory is measured in BITS but is there any other unit to measure computer memory smaller than bits??
In a single word the answer is NO because the measurement of a bit is the status of a single transistor opened at ZERO or closed at ONE.
I would say it is not necassarily a "bit" = binary digit. Just consider an "integrator" analog circuit which can be considered to be part of a computer, an anolog or hybrid one. It computes the time integration of an analog signal say in the range -5/+5 volts. It does"computation" = integration. It does "remember" the past values of the signal. Okay: How much bits this computer have? Is a "bit" still the smallest unit of memory of such a computer? Consider a simple capacitor device. There is no smallest memory represantation of it. It is arbitrarily small. You can have bits only if you "sample" or discritize states or signals. If you don't, then you don't have a smallest one.