Hey @Miley123 I don't think there is an option for server call usage in CJA as CJA reports are built on records that are ingested via Dataset. In Adobe's Customer Journey Analytics, billing is primarily based on the number of data rows ingested and processed within the platform.
Maybe try creating an Alert based on the Events metric and check if it gives the desired results. You can also track usage in the CJA “Connections Usage”, a usage tab adjacent to the connections list.