If you placed one of the multimeter's probes into the hot slot of the wall outlet and touched the other probe to your skin while grounded, for example to some dirt outside, would you get bitten by the current at all?
Would you become a fried chicken dinner, or nah?
That depends on the type of multimeter and mode setting.
Meter is accidentally on Amps mode: You get bitten as if the meter wasn't there.
Additionally, never try to measure amps at a wall socket by putting a probe in each side of a wall socket. It will instantly blow the fuse if the meter has one, or blow the meter otherwise.
Digital and FET multimeters in voltage mode: These have an input impedance of 1 - 10MΩ, some even higher. The highest possible current would be around 200μA for a 230Vac line voltage. This may bite or tickle you but won't be lethal, which is not to say you should try this.
Cheap analog multimeter in voltage mode: These typically have an input impedance of 2kΩ/V. At the 300V scale position, such instrument would have in internal impedance of 600kΩ, which is considerably lower than a typical DMM, so the current would be higher. That only gives about 0.4mA at 230V, which you may not even notice.
At lower voltage settings, the resistance would be lower. The needle will peg immediately in these lower settings, but it will still let the current through. The lower you go, the greater the risk of damage from electric shock.
Electrician's DMM with a low-Z mode (a special voltage mode): The impedance is usually around 5kΩ. That would also bite you as if the meter wasn't there, possibly tripping an RCD.
A cat3 digital multimeter set to Volt ac and with leads connected to COM and Volt prongs, has an input impedance of around 10 MOhm.
If you connect one lead to the hot prong of an outlet, touch the other lead, and touch ground, you would measure the full AC voltage, and not get a shock, but a small current would flow through you.
Some dirt outside will likely not be a good ground. Dry ground is more like an insulator than a conductor. For example a resistance of a stone, or concrete is very high.
The best ground around is the ground electrode at your house, because it was specifically made that way. The ground prong in the outlet is much better grounded than some dirt outside. Water and rain improves ground tremendously.
But even if you are not connected to a ground you will read a voltage, approximately a bit less than half of the voltage in an outlet. This is due to capacitance. Through the multimeter you would get charged to aproximatelly half between the potential in the outlet and a 0 Volt. And because it is an ac, you would keep getting charged to one and then the other polarity, and minute current would flow in and out of you. You would not feel it. Don't try this at home, because a bad meter or a lead in a wrong setting could do you in.
arduino,sensorandmosfettags have next to nothing to do with this question; I suggested a bit more appropriate set of tags. \$\endgroup\$