Hi Bar,
Your requirement can be achieved in the following ways,
Solution 1:
You can achieve this with the help of the crosshairBehavior property in the chart, it will help you to show the current y value on the y-axis in the tooltip. The crosshair will be activated once you touch and hold it anywhere on the chart area. Once activated, it will appear in the UI and move based on your touch movement until you stop touching on the chart. We have shared the online demo sample link and UG documentation below for your reference.
Sample: https://flutter.syncfusion.com/#/cartesian-charts/user-interactions/crosshair
UG, https://help.syncfusion.com/flutter/cartesian-charts/trackball-crosshair#crosshair
Solution 2:
Also, you can show the y-value of the current data point in the chart with the help of the dataLabelSettings property in the series. We have shared the online sample and User Guide (UG) documentation below for your requirement.
Sample: https://flutter.syncfusion.com/#/cartesian-charts/series-features/data-label/default-data-labels
UG, https://help.syncfusion.com/flutter/cartesian-charts/marker-datalabel#data-label
If this is not your case then, please share more information on your requirement in detail, along with screenshots or screen recordings. This will help us assist you in a better way.
Regards,
Yuvaraj.
