I want to show red band values from geo tiff hosted in geoserver. I don't knwo if its possible or not

tiffRaster = new ol.layer.Image({
        title: 'PGA(gal)',
        source: new ol.source.ImageWMS({
            url: 'http://faml.ncn.pe:8080/geoserver/faml/wms',
            params: {
                'LAYERS': 'faml:' + f
            },
            ratio: 1,
            serverType: 'geoserver'
        }),
    });

I tried taking values like tiffRaster.getView() or tiffRaster.getSource() but can't find bands inside. My idea is add a click listener on geotiff to get band value and show it.

This is geoTiff in Geoserver, clicking anywhere it shows value