Scope probes and input circuits have tens of pF capacitance and that will influence the circuit for sure.
If you are only interested in frequency and not an exact shape or voltage levels, you can use a sub-pF capacitor to attach scope to circuit. 2cm of wrapped wires will do the job.
If your oscillator has an inductor, you may just attach 5cm of wire onto scope probe and put it closeby (few mm), it will pick up EM field from inductor. Sometimes even probe itself may pick up the signal.
If this is microcontroller oscillator and you need to touch it with the scope, do use the output pin (OSC2 on PICs).