Sensor to detect rats and mice

The boats are afloat in the harbour or standing on craddles on land.
In rare cases rats and mice find a way over mooring lines into the ship where they can cause immense damage. Because a lot of spaces in a ship are not accesible it's not possible to lay out poisoned lures. If a mouse or rat is detected a trap must be set by hand. The sensor i search must only detect the presence of rats or mice and then my device will send a warning. Besides the great suggestions i see:

-- Ultrasonics not possible (They can hear it)
-- Laser / Lightbarrier (To complicate to mount properly)
-- Cam/TensorFlow (To complicate for me)
-- TOF (Won't work, i have experience with these sensors)

++ Radar/Microwave (Difficult to adjust the sensitivity)
++ PIR (With a switch off during daylight)

I will try with a PIR mounted directly over the floor where humans can't stand to seperate bulglar intrusions / rats 'n mice.
Thx a bunch

Only adult male mice vocalize I believe.

Guess I only met with adults.

@OP: There's a reason that Ship's cats are a thing.

I am 100% sure there are no mouse/rats in my house anywhere.

It's very easy to mount (If there is a space problem then maybe I can't help). You can use the NODEMCU ESP8266 and set an interrupt whenever the receiver signal goes low (mice break the laser line). Then send a alert through WiFi to the phone.