You can capture signals using a PicoScope device. If it has an Arbitrary Waveform Generator, then you can output the stored signal but it will depend on the device as to the number of samples that make up the waveform.
What is the time period of the signal and how many samples would you be looking to capture? What is the voltage range of the signal?
You may wish to look at the following models:
PicoScope 2206/7/8: http://www.picotech.com/picoscope2200-specifications.html
PicoScope 3000 (B and MSO variants): http://www.picotech.com/picoscope-specifications.html
PicoScope 4262: http://www.picotech.com/picoscope4262-specifications.html
I hope this helps.