how to calculate the value of the capacitance of the inverter in cadence???

can anyone tell me how to calculate the capacitance of inverter in cadence???
i m working on 180um tech.
when i simulate the circuit it shows the output file but it doesn't show the value of paracitic capacitance????

Calculations are only as good as data, and good luck getting
that detail from the foundry.

Just simulate it. And integrate the current of the input source
across a transition (for Cin) or the supply source (for dynamic
power, energy per cycle). Bearing in mind that these can vary
by direction of transition and, in more complex gates, logic
state.

Here's another method:
Inject a unit current (1A) into the node whose cap value you want to measure, and run an AC analysis. The voltage [V] vs. frequency plot equates to the magnitude of the impedance Z[Ω] at this node. From any frequency-dependent value you can calculate the cap value.

If the impedance curve comprises a resistive part (horizontal part of the curve at (very) low frequencies, e.g. due to bias generation), the reactive part (of the cap) equals the resistive part at the -3dB frequency of the curve (because conductance and susceptance add quadratically).

You might want to run such an analysis for bias points of both logic states.

PS: Inject the unit current in series with your bias supply, or decouple it via a huge capacitance (e.g. 1F), otherwise it would short-circuit your bias supply.