It is also called a "CT" a Current Transformer.
SCT-013-015: https://www.amazon.com/SCT-013-015-Non-invasive-Current-Sensor-Transformer/dp/B07ZCPMYDL.
It needs a burden resistor and the voltage over the burden resistor is measured.
You also need a certain sample rate to keep up with the 50Hz or 60Hz AC current.
Did you put the Current Transformer over a single wire, or over the cable of the mainline ? Over the cable will not work.
OpenEnergyMonitor about a CT: https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/interface-with-arduino
[ADDED] Oops, jremington already gave that link