How can I measure my advertising campaigns?

Effort and Money put in campaign.- Is your investment

Number of inquires, conversions and time to get those inquires/ customers – Is your return

Also ,at times, the conversion is one or two but the product bought is of high profit margin, then the profit margin should be compared to investment.

And terminology wise,
Common KPIs to measure the campaigns, regardless of the channel, medium or type:
Incremental Sales
Purchase Funnel
Cost per Lead
Customer Lifetime Value
Return on Investment (ROI)
Cost per Win (Sale)
Conversion Rate (or Goal Completion Rate)