Advantages of multifrequency EPR spectroscopy combined with the method of spin labels and probes and also with the method of microwave saturation and saturation transfer for a detailed investigation of the insulating, biological and conjugated polymer systems are demonstrated. Paramagnetic centers being stabilized or/and initiated as nanoscope probe can supply detailed information about structure and dynamics of microenvironment. The correlations of structural, morphological and dynamic characteristics of some polymer systems with magnetic, relaxation and mobile properties of paramagnetic centers embedded into their bulk are revealed. All spin-assisted processes carried out in polymers and their nanocomposites were shown to be defined by the main properties of spin adducts. This can open up new horizons for the creation of efficient scalable organic molecular devices with handled spin-assisted electronic properties.